I'm looking for guidelines for mouse click selection behavior, especially for discontiguous objects. (That is, for a view of objects in arbitrary, unordered locations.) For ordered collections of objects, such a list of items, we have:

Click: select this and deselect others

Shift-Click: extend/shrink anchored selection to include this and all in between

Ctrl-Click: toggle selection of this without affecting others

However, I haven't seen much discussion for discontiguous sets and some of it doesn't agree with practice.

Shift single left-click: For selectable objects, contiguously extends the selection. Otherwise, same as single left-click with possible modifications. For example, in Paint, drawing an oval with the Shift key modifier results in drawing a circle.

Ctrl single left-click: For selectable objects, extends the selection by toggling the selection state of the clicked item without affecting the selection of other objects (therefore allowing selection that isn't contiguous). Otherwise, same as single left-click.

The original Mac UI Guidelines also suggest Shift is the same as Control (Command) for unordered sets.

In graphics applications, objects aren't usually considered to be in any
particular sequence. ... If the user holds down the
Shift key and selects one or more objects that are already highlighted,
the objects are removed from the selection or are deselected.

... If one
of the pieces selected with Command-click is already within an existing
part of the selection, then instead of being added to the selection, it’s removed
from the selection.

Mac OS X Finder exhibits this behavior when selecting items on the desktop.

Questions (In the interest of only one question per Question, consider only the first question as the real question):

It seems odd (as in inefficient) that Shift and Control (Command) behave exactly the same. Is that by intentional design based on research or some accidental legacy standard?

Is there some subtle difference I'm missing between Shift and Control clicking for selection in an unordered collection?

Are there guidelines/precedence for other selection behaviors? For instance, a modifier combination which always adds to selection or one that always removes (mainly useful for click-and-drag rectangle selection over objects of mixed selection states)? I'm told Adobe uses Alt-click for the always-remove behavior, but I can't confirm it.

Are there guidelines/precedence for Alt-click and Control-Shift-click? The above mentioned MSDN doc say don't use them, but surely high-end apps have found them useful.

EDIT: My current rationalization for why the de facto standard includes redundancy is that such views are so rare in most applications that simplicity is more important than expressiveness. In that light, I'm looking for how a specialized application where such views are very common should behave.

1 Answer
1

Personally, I use Windows explorer as my guideline for selection behavior in Windows applications. It's probably the most commonly used Windows application that supports multi-select. And as far as I know, its selection behavior hasn't changed since it was introduced in Windows 95.

I only have Win7 handy and as far as I can tell, Windows Explorer only supports ordered views. Even in icon view (even on the desktop), there is an enforced grid with an order. Maybe I'll try an older WinOS. Or am I missing something in Win7?
–
xanJul 19 '13 at 19:21

I think I misunderstood your question. In re-reading your question and your comment, I'm guessing that you mean selection of objects in an environment where they are randomly placed on the screen (like images on a canvas). I thought by "unordered collections" you mean non-contiguous selection in list.
–
17 of 26Jul 19 '13 at 19:24

Thanks for the info -- I'll see if I can clarify.
–
xanJul 19 '13 at 19:27